Biosynthesis of plant extracellular lipids

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Agriculture worldwide will face many challenges over the coming decades, including those imposed by predicted changes in global climate patterns. In this context, a detailed understanding of plant adaptations that protect them against environmental stresses, such as drought, salt stress and pathogen attack, is critical for generating crop varieties that are more stress resistant. My NSERC Discovery research program is aimed at understanding the biosynthesis in plants of protective surface barriers that are composed of polymerized lipids and associated waxes. These chemically-related barriers are: 1) cuticle coating the aerial surfaces of plants, 2) suberin found in the cells walls of various external and internal tissue layers including roots, and 3) sporopollenin found in the outermost layer of the pollen spore coat. The coordinated activities of a large number of enzymes are required to produce the variety of fatty acid derivatives that form these surface lipid matrices. Over the next five years, my research team will characterize three classes of enzymes producing the following surface lipid molecules: 1) fatty alcohols, 2) free fatty acids, and 3) alkanes (fully reduced hydrocarbon molecules, similar to gasoline). We will also characterize the effects of mutating and over-expressing the genes encoding these enzymes on the ability of plants to withstand environmental stressors. This will give further insights into the structures and functions of plant surface lipid barriers. In addition to providing information and tools for the development of stress-tolerant plants, plant surface lipids are composed of renewable hydrocarbons that are chemically suitable for replacement of petroleum products as sources of energy and chemical feedstocks. Fundamental knowledge of plant surface lipid biosynthesis at the molecular level is critical for harnessing this renewable chemical resource to its full potential. Altogether, the proposed research will provide important fundamental knowledge of a set of plant lipid modification enzymes and insights into the ecophysiological functions of lipid-based surface barriers. In addition, the program will provide advanced training to students in plant molecular biotechnology.